Niacin is essential for keeping our skin and digestive tract healthy, our brain and nervous system functioning normally, certain key cell processes repaired, our adrenal glands producing steroid hormones at demand levels, sex glands producing the hormones estrogen, progesterone and testosterone and, most especially, for producing energy to keep our body alive.1
When absorbed from the small intestinal tract, niacin becomes part of a process including more than 200 enzymes involved in metabolism of carbohydrates, proteins and fatty acids, that is, chemical reactions that maintain life.1 Niacin is stored by the liver.2
Niacin must be digested to release its absorbable forms, nicotinamide and nicotinic acid. These molecules are absorbed across the intestinal lining at low concentrations by sodium-dependent facilitated diffusion, meaning they need help to get into the bloodstream.1 Niacin is absorbed at higher concentrations by passive diffusion, meaning the niacin molecules simply cross through the lining.2 That said, absorption is hampered by the swelling and thickening of the intestinal lining that occurs in celiac disease. Removing gluten reduces the inflammation and allows the lining to heal, facilitating passage of niacin through the lining into the bloodstream.
|Intriguing animal research by Sandhur et. al. has shown that niacin deficiency itself sensitizes the intestinal mucosa of rats to gluten in wheat, barley, rye, oats and corn and induces susceptibility to gluten toxicity by means of cellular dysfunction.3 Human research needs to investigate this effect of niacin deficiency in human celiac disease.|
Niacin deficiency due to malabsorption is common in celiac disease before gluten is removed from the diet.1 Niacin deficit can be aggravated by a lack of niacin, or the amino acid tryptophan, in the diet. Our body uses tryptophan to make niacin as a back up mechanism. Smoking also impairs absorption of niacin.2
Lack of niacin in the diet comes from choosing foods that are low in niacin. An example of how this can happen is if we used plain corn flour rather than masa flour for baking gluten-free recipes and purchased tortilla chips, tacos and snack foods made from plain corn flour. Plain corn flour is low in niacin and its niacin cannot be digested. Whereas, the niacin in masa flour is made digestible. Masa is the result of soaking corn in lime, a strong alkali that releases the bound niacin so that it can be digested.2 Lime would be listed as an ingredient on the product’s nutrition label.
Lack of tryptophan in the diet is due to choosing foods that lack this amino acid and avoiding those that are rich in tryptophan, such as eggs and meat. Conversion of tryptophan to niacin requires adequate levels of tryptophan and adequate levels of iron, riboflavin, or vitamin B6.2 Tryptophan-to-niacin conversion can easily be subverted if tryptophan itself, or the co-factors iron, riboflavin or vitamin B6, are deficient.
Inadequate levels of niacin slows metabolism and impairs functioning of the brain and nervous system, digestion, skin, DNA repair and other key cell processes, and steroid and sex hormone production. Severe deficiency of niacin causes the disease pellagra.2
Mild Niacin Deficiency Symptoms:
- Problems with metabolism: muscle weakness, lack of energy, weight loss, decreased tolerance to cold.
- Problems with the nervous system: irritability, dizziness, fatigue, poor concentration, poor memory, anxiety, apathy, depression, headache, neuritis (numbness, burning in various parts), tremors, restlessness and hyperactivity in children.
- Problems in the digestive tract: anorexia, distorted taste, indigestion, scarlet colored tongue, burning of the mouth, throat, and esophagus, abdominal discomfort and distention, nausea, diarrhea or constipation.
- Problems with the skin and mucous membranes: sensitivity of skin exposed to sunlight causing a red, itchy, scaly rash that resembles mild sunburn, and inflammation of mucous membranes of vagina and urethra.1
Severe Niacin Deficiency Symptoms (Pellagra):
Severe niacin deficiency is called pellagra. Pellagra is characterized by the classic 4 “Ds”…watery Diarrhea, severe Dermatitis, advancing Dementia and Death.
- Diarrhea can be bloody and other digestive disturbances worsen with vomiting.
- Dermatitis develops symmetrically in areas exposed to sunlight with hyperpigmentation (dark color), thickening and cracking of the skin, itchy red wet areas from chafing, and “necklace” sores on the lower neck.2 Subcutaneous fibrosis and scarring within the skin may be seen in late stages. A bright red swollen tongue which in chronic stage is fissured and is similar to raw meat.4 Inflammation of other mucous membranes worsens with increasing deficit.
- Dementia is due to neuronal loss (death of nerve cells) with development of amnesia, disorientation, confabulation, and delirium.
- Death ensues eventually if the niacin deficiency is left untreated.2,3
Food Sources of Niacin5
Excellent Animal Sources:
Beef liver, pan fried 17.5 mg
Pork liver, pan fried 15.3 mg
Chicken breast, fried 14.8 mg
Chicken liver, fried 13.9 mg
Turkey liver, pan fried 13.5 mg
Tuna, light, canned in water 13.3 mg
Veal liver, pan fried 13 mg
Bacon, pan fried 11.6 mg
Very Good Animal Sources:
Venison steak, pan fried 10 .75 mg
Veal shoulder 10.7
Pork chops 10.2
Duck 10.4 mg
Salmon 10 mg
Trout 8.79 mg
Beef sirloin 8.7 mg
Australian lamb loin 8.2 mg
Ham, boneless 5.9 mg
Oyster 3.6 mg
Clams 3.4 mg
Very Good Plant Sources:
roasted peanuts 14.7 mg
roasted sunflower seeds 7 mg
mixed nuts with peanuts 5 mg
sesame seeds 4.6 mg
portabella mushrooms 4.6 mg
grape leaves 4.5 mg
almonds 3.9 mg
Good Plant Sources:
Brewer’s yeast ONLY if made from sugar, therefore, gluten-free.
If brewer’s yeast is a by-product of beer, it’s not gluten-free.
Milk and eggs are poor in niacin but rich in tryptophan, which the body can use to make niacin.6
Comparison of Niacin Amounts in 100 mg of Various Flours1
Rice bran 34 mg
Peanut flour 11 mg
Buckwheat flour 7 mg
Brown rice flour 6.3 mg
Soy flour 3.3 mg
Sorghum flour 2.9 mg
Quinoa flour 2.9 mg
White rice flour 2.6 mg
Corn flour 1.9 mg
Chickpea flour 1.8 mg
Amaranth flour 1.3 mg
Wheat flour 1.3 mg*
(Wheat flour is bound, like corn, which is why it must be commercially fortified.)
Recommended Dietary Allowances for Niacin. 2
Children 1 to 3 years: 6 mg
Children 4 to 8 years: 8 mg
Children 9 to 13 years: 12 mg
Males 14 to 18 years: 16 mg
Females 14 to 18 years: 14 mg
Males 19 years and older: 16 mg
Females 19 years and older: 14 mg
Pregnant females: 18 mg
Breastfeeding females: 17 mg
Getting Your Daily Intake
As with any supplement, discuss your optimum dose of niacin with your doctor.
In addition to making foods rich in niacin a part of your healthy diet, consider taking a multivitamin preparation containing 100% to 300% RDA in order to make up for any shortfall. Do not give niacin or any other supplement to a child without consulting a doctor.
Besides availability in multivitamin preparations, niacin is also provided as part of B-complex vitamin preparations and as a single vitamin preparation of niacinamide. Take supplemental niacin with a meal for best absorption.
Safety and Toxicity
There is no evidence that niacin from foods causes adverse effects.
If you take prescription medicine, there is a potential for side effects and interactions with all supplements.
Prolonged treatment with the anti-tuberculosis drug, Isoniazid, has resulted in niacin deficiency. Other drugs which interact with niacin metabolism may also lead to niacin deficiency. These include tranquillizers (diazepam) and anticonvulsants (phenytoin, phenobarbitol). 2
Niacinamide preparations less than 50 mg have low toxicity and excess niacin is passed out in the urine.
Nicotinic acid preparations in pharmacological doses used as cholesterol lowering medicine, but not nicotinamide, exceeding 300 mg per day have been associated with a variety of side effects including nausea, diarrhea and transient flushing of the skin caused by histamine release. Doses exceeding 2.5 grams per day have been associated with liver toxicity, glucose intolerance, elevated blood sugar, elevated blood uric acid levels, heartburn, nausea, and headaches. Severe jaundice may occur, even with doses as low as 750 mg per day, and may eventually lead to irreversible liver damage. Doses of 1.5 to 5 g/day of nicotinic acid have been associated with blurred vision and other eye problems. 2
Although prescribing large doses of 4 to 6 grams of niacin in cholesterol lowering medications has grown increasingly popular, our body only needs 14 to 16 milligrams every day.
Impact of Storage, Processing, and Cooking
Both nicotinamide and nicotinic acid are stable when exposed to heat, light, air and alkali. Little loss occurs in the cooking and storage of foods.2
Copper deficiency can inhibit the conversion of tryptophan to niacin.2
2. Niacin by National Academy Press accessed at http://www.nap.edu/openbook.php?record_id=6015&page=123
3. Sandhur JS, Fraser DR. Effect of dietary cereals on intestinal permeability in experimental entteropathy in rats. Gut. 1983 Sep;24(9):825-30.
4. Complications of Niacin Deficiency by Dr Sampurna Roy and Prof. H Roy accessed at www.surgical-pathology.com
5. Glutenfreeworks.com. Nutrition Guide. http://www.glutenfreeworks.com/nutrition_guide.php.
6. Kathleen Mahan and Sylvia Escott-Stump, ed. Krause’s Food, Nutrition, & Diet Therapy, 10th Edition. Philadelphia, PA, USA: W.B. Saunders Company, 2000.